A PLC-based pomegranate sprout removal device design

Aiming at the current low degree of mechanization of pomegranate sprouting tiller pruning in China, all relying on manual pruning, this paper designs a PLC-based pomegranate sprouting tiller removal machine. This machine adopts the identification method of wireless map transmission, the sprouting tiller removal method of multi-cylinder cooperative operation, and the MCGS configuration to realize the interaction between the user and the system, which realizes the displacement and angle compensation of the end-effector under complex conditions to realize the all-around accurate removal of the pomegranate sprouting tiller. The performance test and finite element analysis showed that the device could remove up to 74.62% of sprouting tillers, and the damage rate was as low as 18%. This meets the requirements of pomegranate plantations for the removal of emergent tillers.


Overall structure and workflow
This study aims to design a pomegranate sprout cutting device based on PLC.First, through on-site investigation of the growth height of pomegranate trees, diameter of pomegranate sprouts, and height of most sprouts, combined with existing sprout cutting equipment on the market, SolidWorks 2020 was used to establish a model of the relevant structure of pomegranate tree sprout cutting equipment.Then, FluidSIM-P 3.6 pneumatic simulation software was used to conduct simulation experiments on the pneumatic part of the equipment and the electrical control part that controls the reversal of the pneumatic part; second, the electrical control part and stepper motor control part were connected to the corresponding parts of the FX3U-32MT PLC, control was simulated through GX works2 programming software, and a monitoring interface was created through MCGS configuration software 6.2.Transfer the produced monitoring interface to the FX3U-32MT PLC and then enter the operating environment for the simulation control.Finally, debugging and operation of the overall key parts will be carried out, and the first-generation prototype will be manufactured and tested after the entire machine is correct.The technical research route used in this study is shown in Fig. 1.
A PLC-based pomegranate sprout cutting machine was designed based on relevant data of pomegranate trees and sprouts.The machine is mainly composed of a primary lifting device, secondary lifting device, multi degree of freedom sprout cutting device, leaf-shifting device, pneumatic control system, and MCGS control system.The overall three-dimensional mechanism is illustrated in Fig. 2.This device can perform image recognition based on equipped wireless image transmission equipment to determine the growth position of sprouts on pomegranate trees in complex states.Then, through the manual operation of the MCGS control panel, the first-level lifting platform can be roughly adjusted higher, and the second-level lifting platform can be precisely adjusted higher.Furthermore, a multi degree of freedom cutting mechanism can be controlled to complete the cutting of sprouts in complex states.
The working process of the device is divided into four stages: First, the lowest machine was pushed to the bottom of the pomegranate tree by humans.
1.The camera identifies the location of pomegranate sprouts and determines the sprouts and their positions that need to be removed; 2. The camera provides real-time feedback of sprout images to the screen connected to the MCGS screen and adjusts the primary and secondary heights by manipulating the MCGS buttons to ensure that the height is within the appropriate cutting range.3.By controlling the MCGS control panel, the multi degree of freedom sprout cutting device was controlled to achieve the cutting of all sprouts that needed to be cut within this range.4.After the cutting was completed, the heights of the first and second levels were adjusted according to the actual cutting needs of the pomegranate tree sprouts.Repeat operation 3 and perform secondary cutting or multiple cutting.
Working principle: The first-level lifting platform uses a single cylinder for rough control of lifting position.The secondary lifting platform was controlled using four stepper motors to accurately reach the desired position.Mutual cooperation can achieve sprout removal at different height ranges.www.nature.com/scientificreports/

Workflow analysis and main technical parameters
The operator pushes the sprout cutting machine under the pomegranate tree, which must be cut off before leaving.The machine starts, and the real-time image transmission camera displays the position of the sprout in the pomegranate tree on a display screen connected to the manually controlled MCGS.Experienced staff operated the MCGS to determine the position of the sprout and then proceeded with sprout cutting.The specific removal process is as follows.The real-time image transmission function of the camera displays the position of the sprouts in real time, and when the nearest height position is manually determined, control and adjustment are performed.First, the first-level height lifting device is adjusted, the overall height is adjusted to the approximate position height, and then the second-level height adjustment is performed.The second-level height adjustment mechanism had a higher accuracy than the first-level adjustment mechanism.Through the cooperation of the first-and second-level height adjustment mechanisms, the height position of the end effector is adjusted to the appropriate range so that the end effector can cut all the required sprouts within the height range.After all sprouts that need to be cut off within the height range are cut off, the staff will perform the above operation again, raise the machine height to the next height range, and cut off the sprouts within the height range.When cutting: The end-effector structure adopts a multi cylinder collaborative multi degree of freedom end effector.The operator can control the operation panel on the MCGS to retract each cylinder, thereby achieving the goal of clearing all sprouts of pomegranate trees under various growth conditions.After the machine removed all sprouts of www.nature.com/scientificreports/pomegranate that could be cut, the operator stopped the machine, stopped the air pump, and pushed it out to the appropriate position.The workflow is illustrated in Fig. 3.
The main technical indicators of the pomegranate sprout cutting machine are presented in Table 1.

Design of primary lifting device
The first-level lifting device consisted of two sets of frames with rollers and cylinders, which were connected to the middle of the lifting device through fixed hinge supports.As shown in Fig. 4, the SC80-500 cylinder was selected as the power source, powered by an air pump, to perform rough lifting within the range, achieving the first-level height adjustment of the pomegranate sprout cutting machine to most of the sprout growth range, and laying a certain foundation for the subsequent second-level precise lifting device to find suitable cutting positions.
According to relevant data on pomegranate trees, the distribution range of pomegranate sprouts is 2 m, that is, the distance difference between the lowest and highest sprouts of pomegranate is 2 m.Therefore, the lifting range of the cutting machine should be at least 2 m.Therefore, the design range of the first-level lifting device is approximately 1.2 m, and that of the second-level lifting device is approximately 0.8 m, which can meet the needs of most pomegranate trees for sprout removal.
The range that the first level lifting device can provide for machine lifting is not less than 1.2 m.Based on this, combined with the relevant parameters of the cylinder and installation position, the bottom design size of the lifting device can be calculated, and then the overall size of the prototype can be designed to make its layout reasonable and structure reliable.A schematic of the mechanism can be obtained by drawing a three-dimensional model, as shown in Fig. 5.
To prevent the roller from detaching from the slide when the workbench is lowered to the lowest position, the length of the hinge plate 2 L should be smaller than the length b of the workbench, which is generally acceptable.From Fig. 5, it can be seen that h = 2Lsinα.It can be concluded that: The effective vertical ∆h stroke of the lifting table is: Cylinder model SC80-450 was selected, with a length of 632 mm when contracted and a distance of 1082 mm when extended to the longest.The position of the cylinder was set in the middle of the lower bracket, as shown in the structural diagram above.Ignoring the length of the fixed hinge supports at both ends, it was assumed that the longest and shortest dimensions of the cylinder were the shortest and longest, respectively.Combining Eqs. ( 1)-( 6), the maximum and shortest stretching distances of the known cylinder, as well as the distance of ∆h, should be taken into account.The value of ∆h should be ≥ 1.2 m, and a critical value of 1.2 m should be selected here.
The value of L can be calculated by incorporating the above formula into MATELAB: L = 1135 mm.According to Eq. ( 1), b = 2365-2552 mm.The connecting rod of the two fixed racks was set to a length of 2270 mm and the bottom surface was set to 2450 mm × 1000 mm.

Rotating platform design
The design function of the rotating platform is to enable the multi degree of freedom end effector of the upper part to rotate around the z-axis, giving it a wider range of shear sprouts.Its structure is shown in Fig. 6.To ensure smooth operation of the rotating platform, a hollow turntable of the rotating platform was installed at the upper connecting plate, and the stepper motor was installed above the lower connecting plate.The upper and lower connecting plates were fixed to the slider of the screw module on the secondary lifting device with bolts to ensure the stability of the entire mechanism.
To improve the practicality and reliability of the rotating platform, the rotating device adopts a 14 inch 360° galvanized circular hollow turntable with its top connected to a multi degree of freedom end effector.Then, the bottom of the end effector was welded to a connecting shaft and connected to the lower stepper motor through coupling.This allows the stepper motor to move the upper end effector in the same direction during the movement.Because the weight of the upper end effector is approximately 40 kg, considering safety and the additional ( 5) www.nature.com/scientificreports/force during rotation, a 14 inch hollow turntable was chosen, which can withstand a weight of up to 100 kg.The actual object diagram is shown in Fig. 7.
The rotational power of the rotating platform was provided only by a stepper motor connected to it.The selection of the fixed stepper motor is particularly crucial because the required accuracy of the stepper motor is not high, and its function here is only to rotate the rotating platform.When selecting the fixed stepper motor, only the step angle and torque were used for rough selection.
Firstly, the step angle α should satisfy: In the formula, i is the transmission ratio; α min is the minimum angle required by the system for the components driven by the stepper motor.
Because the stepper motor is only directly connected to the welding shaft under the end effector through coupling, the transmission ratio i = 1 is fixed.Owing to the low accuracy requirement for the required rotation angle, the fixed angle only needs to be selected from the smaller step angles.
Second, for the stepper motor to operate normally (without losing step or stepping over), start normally, and meet the speed requirements, the starting torque T q must meet In the formula, T m is the static load torque of the motor; The load torque can be obtained from Eq. ( 9) as T m : where J is the Moment of inertia of the load; To facilitate the calculation, all components of the upper end actuator can be converted into a solid cylinder to calculate its moment of inertia Jx.As mentioned earlier, the end effector mentioned above weighed approximately 40 kg, and 45 # steel was used as the manufacturing material, with a density of 7.85 g/cm 3 .It can be converted into a 45 # steel rod with a bottom radius of 300 mm and height of 22 mm.The Moment of inertia J can be obtained from Eq. ( 10): Substituting the data into formulas ( 8)- (10).As the control here is an inching control, there is no angular acceleration.Press the touch screen to rotate the motor over a step angle corresponding to its angular acceleration.After taking the step angle of two-phase hybrid stepping motor and other relevant parameters, the starting torque T q ≥ 10.8 Nm can be obtained.By searching for relevant tables, it can be seen that the selected stepper motor model is the 86BYG250H stepper motor with a holding torque of 12 Nm, which meets the usage requirements.
The purpose of setting the secondary lifting device is to make slight height adjustments to the end effector when it reaches the approximate range where sprouts exist, to achieve a more precise height and achieve precise removal of sprouts.A 3D model image is shown in Fig. 8.
The mechanical structure of the secondary lifting device consisted of four screw modules and an aluminum profile frame.To set up this device, when the end effector runs to the approximate range where sprouts exist, slight height adjustments are made to achieve a more precise height, thereby completing the precise removal of sprouts.Therefore, the device only needs to ensure that it drives the end effector to rise and that the rising distance is within a small range each time.
As mentioned above, the total weight of the end effector, connecting plate, and stepper motor is approximately 50 kg.The SGX series single-track ball screw slide table was selected, and the model selection was 1605-600.The maximum vertical load of a single unit was 15 kg.Owing to the installation of four ball-screw modules in the device, the total weight that the fixed device can withstand is 60 kg ≥ 50 kg, which meets the requirements www.nature.com/scientificreports/ of the device design.In addition, the 1605 model represents a diameter of 16 mm for the screw and a pitch of 5 mm, which means that for every revolution of the stepper motor, the device increases by 5 mm, meeting the accuracy requirements for use.The specific physical framework construction is shown in Fig. 9, which shows the secondary lifting device connected to the stepper motor driver and the PLC.

Design of pneumatic multi degree of freedom end effector device
The purpose of designing a pneumatic multi degree of freedom end effector is to achieve multi angle and allround cutting of pomegranate sprouts.Its mechanical structure consists of three cylinders: the shear arm swing angle adjustment cylinder, extension adjustment cylinder, scissors angle adjustment cylinder, and pneumatic scissors set on the upper part of the extension adjustment cylinder, as well as the camera next to it.The threedimensional mechanical structure model is shown in Fig. 10.
The function of the camera in the end-effector device is real-time image transmission, which plays a role in real-time image feedback, determining the position of pomegranate sprouts, and facilitating machine cutting.It consists of a transmitter, an image transmission module, and a display terminal.The purchased physical image is shown in Fig. 11.The transmitter simulates and modulates the video signal and sends it wirelessly to the receiver, which demodulates and sends the signal to the display terminal.Select a 5.8G image transmission module, select the optimal eight channels for frequency modulation, with 20 frequency differences between adjacent channels, stable, efficient, and interference-free, with a small size, low power consumption, and high sensitivity.A camera is installed at the end effector.When the operator controls the end effector, the camera feeds back the environment inside the pomegranate branches and leaves, as well as the number and position of surrounding sprouts, to the screen.When there are sprouts in the pomegranate tree that need to be cut off on the screen, the operator can use the MCGS to control the cylinder and complete multi-angle sprout cutting.
Among the three cylinders of the pneumatic end effector, the most important consideration and selection design was the elongation adjustment cylinder.Because the cylinder is directly connected to the pneumatic scissors and related connectors, the force borne by the cylinder is the largest of the three cylinders, and its elongation distance directly determines the range of cutting off the sprouts of the end effector.Therefore, the selection and design of cylinders should be emphasized.According to the growth range of pomegranate sprouts, the position  www.nature.com/scientificreports/ of the higher sprouts is about 2.5 m, and the height that can be lifted and lowered is determined to be 2 m by the first and second level lifting platforms mentioned above.The stroke of the designed elongation cylinder is 600 mm.When the shear arm swing angle adjustment cylinder is perpendicular to the machine plane, it can reach a maximum cutting height of 2.6 m, meeting the cutting needs of most pomegranate tree sprouts.Using Festo's official online software for the simulation calculation, a stroke of 600 mm was selected, and the motion time was fixed at 30 s because of the device's jog control, which means the running distance per second was 20 mm.The air source pressure to 0.6Mpa, and the motion mass was set as pneumatic scissors and related connectors.It is roughly estimated to be 5 kg, set to the ideal state, and the friction force to be 0N.Using the DSBC-32-600-PSA-N3 cylinder for simulation, the relationship between displacement velocity and time, as well as acceleration and time, can be obtained, as shown in Table 2(a) and (b).After the simulation, it can be concluded that its motion time is 31.573s, with an average velocity of 0.020 m/s, an end impact velocity of 0.021 m/s, and a maximum velocity of 0.150 m/s.
From the above simulation calculations, it can be concluded that the point at which the cylinder is subjected to the maximum force occurs.As acceleration occurs at the moment of cylinder startup, it can be seen from Table 2(a) that the maximum value of acceleration, amax, is approximately 6 m/s 2 .As the load only drives pneumatic scissors, which is 5 kg, and the total weight of the cylinder, including the weight of the cylinder and the weight of the cylinder connecting parts, is about 20 kg, with a fixed Fmax of 150 N, According to the relevant manual of the cylinder, it can be seen that at 0.6 Mpa, the theoretical maximum force that the cylinder can withstand is 483N, which is greater than Fmax.Therefore, it is feasible to select this type of cylinder.A physical image of the pneumatic end-effector is shown in Fig. 12.
The function of the pomegranate sprout cutting auxiliary mechanism in the device is to move the branches blocked in front of the device so that the end actuator can cut the sprout more accurately.Its mechanical structure is composed of a toggle cylinder, core toggle frame, toggle plate, and toggle seat.By controlling the expansion     www.nature.com/scientificreports/and contraction of the cylinder, the toggle frame drives the toggle plate to make a circular motion to move the leaves and branches blocked in front.The three-dimensional model structure is shown in Fig. 13.

Design of pneumatic circuit system
The pneumatic circuit of pomegranate sprout cutting equipment uses high-pressure gas as the working medium for energy transfer.It controls the orientation of the end effector through three double-acting cylinders, achieving adjustment of the height, length, and angle of the end effector.The auxiliary blade-cutting device was controlled by two double-acting cylinders for blade shifting.The primary lifting function is achieved through a lifting cylinder, and pneumatic components, such as pneumatic scissors for cutting sprouts, are used as power devices to form a unified overall pneumatic circuit.Then, a programmable controller PLC FX3U-32MT was used to control the equipment.A total of six cylinders and one pneumatic scissor are required for the equipment.Through cylinder expansion control, the machine can cut off pomegranate sprouts in multiple directions, angles, and heights, and timely determine and move the position of sprouts and branches that need to be moved through the real-time image transmission system.The principle of the pneumatic main circuit of the equipment is illustrated in Fig. 14.

Design and wiring of stepper motor system
The pomegranate sprout cutting equipment was based on a PLC FX3U-32MT control.In this PLC model, y0, y1, and y2 are the pulse output points in the PLC.Therefore, during wiring, one main 86 rotating platform stepper motor rotating platform and four secondary lifting device stepper motor lifting tables need to be connected to the pulse output points y0, y1, and y2, and y3, y4, and y5 are connected to the stepper motor direction port.
The pulse output point of the y0 output on the PLC FX3U-32MT is connected to the stepper motor pulse PUL on the stepper motor driver.Because COM1 on the PLC is connected to the 0v of V switching power supply, PUL + on the stepper motor driver is connected to 24 V, and the y3 output on the PLC is connected to the direction DIR-on the stepper motor driver.The DIR + on the stepper motor driver was connected to PUL + in parallel for 24 V. GND and V + are the working power supplies for the stepper motor drivers, and 24 V and 0 V are connected to the terminals of GND and V + , respectively.
The stepper motor driver has the advantages of increasing the output torque of the motor, a high starting frequency, strong driving reliability, low cost, and wide use.The stepper motor dial switches SW1, SW2, and SW3 output current settings, with peaks representing the full current and RMS representing the half current.Generally, the output current is in the form of half-current.SW4 control selects half of the current or full current output current.The SW4 dial is set to off to half the current output, the SW4 dial is set to on to full current output, and the SW5 SW6, SW7, and SW8 pulse output settings.
The 57 stepper motors selected for this device were 1.5A, with a step angle of 1.8°.The stepper motor sends every pulse to the stepper motor driver to rotate by 1.8 degrees.Therefore, in an ideal state, the stepper motor must send 200 (360/1.8)pulses for one revolution.However, in reality, the stepper motor output loses its steps.Therefore, to compensate for this problem, the stepper motor divides the step angle into M equal parts, One subdivision of 1.8/1 = 1.8 degrees sends 200 (360/1.8)pulse stepper motors for one revolution, two subdivision of 1.8/2 = 0.9 (360/0.9)degrees sends 400 (360/0.9)pulse stepper motors for one revolution, four subdivision of 1.8/4 = 0.45 degrees sends 800 (360/0.45)pulse stepper motors for one revolution, and so on.When debugging the equipment, we chose to send every 5000 pulse stepper motors for one revolution to improve the rotation accuracy of the stepper motor.

Design of PLC control system for the entire machine
The system adopts PLC FX3U-32MT for cutting control of pomegranate sprouts, which requires the control of five stepper motors, four double-acting cylinders, and one pneumatic scissor.
According to the different input and output states, four two-stage lifting device 57 stepper motors that adopt collaborative control are selected for the equipment.Therefore, two of them are connected to the pulse output  www.nature.com/scientificreports/port of the same programmable controller, and the main 86 stepper motor are connected to the pulse port of the programmable controller.A PLC with three pulse output ports was required.Controlling the output status of the cylinder requires an electromagnetic directional valve as a control element, which requires a coil-type PLC.
It is necessary to select the control hardware with a coil output port, and the input ports are all inputted using the MCGS touch screen.Therefore, two PLCs (FX3U-32MT) were selected.
The PLC control process is illustrated in Fig. 15.The entire machine was controlled using the MCGS touchscreen jog control, which achieved precise positioning and cutting of the cutting position.The height, length, and angle adjustment cylinders determine their control sequences based on actual situations.

Kinematics simulation analysis of auxiliary resection device
The uncertainty of the direction of the pomegranate tree branches when they grow to form a disorganized and complex spatial structure leads to the complexity of the operating environment of this apparatus for cutting pomegranate sprouts.Therefore, when performing the operation, the target branch is prone to interference from the remaining branches.At the same time, the spatial movement of the robotic arm is restricted, making it difficult to contact the target branch to be removed.To eliminate the interference of other branches on the target branch and robotic arm, a pneumatic-assisted resection device was designed, which mainly consisted of a toggle cylinder, core toggle frame, toggle plate, and toggle seat.The toggle seat is fixed to the rotating disc of the device, and through the extension and contraction of the cylinder, the end of the core toggle holder is swung with the hinge connection with the toggle seat as the center, which finally achieves the swing of the toggle plate.
The most critical parts of the auxiliary cutting mechanism are the toggle cylinder and core toggle part.The motion in SolidWorks was used for the kinematic analysis of the toggle cylinder, and the simulation finite element analysis was used for the static analysis of the core toggle part.First, a DSNU-12-200-P-A cylinder was selected from the Festo series as the driving cylinder for the auxiliary device.In Motion, the cylinder was set as a linear motor driver, and the entire auxiliary device uses 45 # steel as the component material.Owing to the use of the inching control for the cylinder control, the speed of the driver was set to 30 mm/s, and the time to reach the maximum output was set to 6 s.The calculation results are illustrated separately, and the relationship between the speed, force on the linear motor (cylinder), and displacement with time is shown in Table 3(a-c).
From Table 3(a), it can be observed that the maximum speed of the paddle plate is 115 mm/s, which meets the requirement of moving and obstructing tree branches.From Table 3(c), it can be observed that the maximum force on the cylinder is 14 N, which occurs at the end of the cylinder movement.According to relevant manuals, the maximum force on the cylinder of the DSNU-12-200-P-A model when extending and retracting is 50.9N and 67.9 N, respectively.Therefore, the selected model cylinder met its usage requirements and was reasonably designed.

Statics simulation analysis of auxiliary resection device
After completing the 3D modeling of the auxiliary cutting mechanism, mechanical analysis was performed on the relevant load-bearing parts.As mentioned earlier, the core component of the auxiliary cutting device was the core toggle frame.In order to ensure its stable force and no significant displacement deformation during operation, in this paper, the finite element simulation of the core toggle frame was carried out after the design of the part using ZWMeshworks2023 structural simulation software with Lanczos eigenvalue method solution www.nature.com/scientificreports/matrix.Firstly, in ZWMeshworks2023, the model of the toggle leaf version in Solidworks is imported, and then a new linear static analysis task is created to set the toggle leaf version model material as AISI 1045 steel, and its physical properties are shown in Table 4.
The network division of the dialleaf version is then carried out by ZWMeshworks2023, and the network division settings for the dialleaf version in this study are shown in Table 5, which are generated as shown in Fig. 17a.
To better understand the force of this structural member in the device, as shown in Fig. 16.In this study, by constructing a motion sketch of this device, motion analysis of this device is carried out to more accurately set the mechanical load and constraint state of the core toggle frame.
Analyzing the entire motion process, it can be seen that in the initial state, the core toggle frame is subjected to the minimum force, and at this time, the cylinder has no thrust effect on the bottom end of the core toggle frame.When the movement begins, the gravity force of the toggle plate is converted to the pressure on the core   www.nature.com/scientificreports/toggle frame; at this time, the lower end of the push cylinder on the core toggle frame thrust gradually increases; when the movement to the highest height, the gravity force of the toggle plate is converted to the core toggle frame pressure; at this time, the cylinder extends to the longest height, and the thrust force reaches the maximum, solid at this time, the core toggle frame by the maximum force.At the same time, in the working process, the core toggle frame middle hole position of the realization of the hinge is fixed and rotated around its position, as well as in the movement to promote the version of gravity on the maximum impact of this piece, ignoring the movement of the cylinder parts, only to analyze the linear  www.nature.com/scientificreports/displacement of the paddle plate to arrive at the limit value; the force received by the cylinder also reached a maximum value of 14N, the core toggle frame of the force, so this paper on the core toggle frame middle hole position set up hinged fixation in the connection between the cylinder and the core toggle frame to set up the fixed constraints, as shown in Fig. 17b.Finally, the structural simulation results are calculated in ZWMeshWorks2023 for the processing as described above, and the results of the stress and displacement analyses are obtained, as shown in Fig. 18.
According to Fig. 18, the maximum stress on the core toggle frame was 111.9 MPa, and the maximum displacement of the core toggle frame during the stress was 0.2063 mm.According to the physical information of AISI 1045 steel in Table 4, the maximum stress on the core toggle frame is much less than the yield strength of AISI 1045 steel, and the strain is within the allowable range; therefore, the design of the solid-core toggle frame meets the usage requirements.requirements.

Experimental materials, conditions, and equipment
To complete the final experiment of the machine and test whether the multi degree of freedom end actuator can work normally, a pruning test was conducted in the engineering training building of Liaocheng University in April 2023 for trees with similar heights to pomegranate trees.The height of the branches and leaves of the experimental trees was 2-3 m.The power was selected from the German Komax 220v small oil-free silent air compressor with a power of 1490w and a maximum pressure of 0.8 Mpa.The power supply was a 220-2500 W outdoor mobile power supply, which supplied power to the air pump and electric components in the machine.The selected prototype was the pomegranate sprout cutting device studied in this study, as shown in Fig. 19, and the measuring tool for measuring the diameter of sprouting branches was a tape measure.

Evaluating indicator
The pruning rate and damage rate were selected as evaluation indicators to intuitively demonstrate the cutting effect and quality of the pruning machine.Each indicator is the average of multiple experiments and is defined as In the formula, P 1 represents the pruning rate of the entire tree's sprouts, %.Z 1 is the actual number of sprouts cut by the machine.Z is the total number of sprouts that must be cut within the entire tree.
where P 2 is the damage rate of non-sprouting branches of the entire tree,%.Z 2 is the total number of damaged non sprouting branches.Z 3 is the total number of non sprouting branches of the entire tree.

Orthogonal experiment
To optimize the parameters and determine the interactivity between experimental factors, the range of experimental factors, such as sprouting diameter A, air pump working pressure B, and cylinder operating speed C, were determined through calculation and analysis.A three-factor, three-level quadratic regression orthogonal experiment was conducted with shear rate P 1 and damage rate P 2 as the response values.The experimental factor codes are listed in Table 5.
Using Design Expert software for data analysis and processing, the results of the three-factor and three-level experiments designed based on the Box-Behnken experimental principle are presented in Table 6.( 11) www.nature.com/scientificreports/Using Design Expert software, multiple linear regression and quadratic fitting were performed on pruning rate P1 and damage rate P2 of pomegranate sprouts.The quadratic regression equations for P1 and P2 were obtained, as shown in Table 7.
Using Design Expert software for the regression equation analysis of variance simulation, Tables 6 and 7 were obtained.From Table 8, it can be seen that the quadratic regression model of the pruning rate of the pomegranate sprout cutting machine (P < 0.05) indicated that the regression model was significant.Analysis of variance showed that the sprout diameter (P < 0.05) had a significant impact on the shear rate.The cylinder running speed (P < 0.05) indicates that the cylinder running speed has a significant impact on the shear rate.Analysis of variance shows that the significance of each factor on the shear rate is in descending order: sprout diameter and cylinder running speed.The pressure of the air pump had no significant impact.
From Table 9, it can be seen that the quadratic regression model for the damage rate of the pomegranate sprout cutting machine (P < 0.0001) indicated that the regression model was extremely significant.Analysis of variance showed that sprout diameter (P < 0.05) had a significant impact on the damage rate.A cylinder operating speed of P < 0.0001 indicated that the cylinder operating speed had a significant impact on the damage rate.Analysis of variance showed that the significance of each factor on the shear rate was in the following descending order: air cylinder operating speed and sprout diameter.The working pressure of the air pump had no significant impact.The AC interaction term has a significant impact, proving that there is an interaction between the sprout diameter and cylinder operating speed on the damage rate.

Response surface analysis
Using Design Expert software for solution optimization analysis, the optimal solution was obtained, which was achieved when the average diameter of the sprouts was 2.684 mm, working pressure of the air pump was

Discussion
This paper presents a systematic description of the overall structure and workflow of a machine that consists of a camera that determines the position of the pomegranate sprouting tiller and transmits it to a display screen, a primary and secondary lifting platform, a multi-degree-of-freedom end-effector, and an auxiliary leaf-shifting device.Simulations and finite element analyses were performed to determine the structural soundness of this study.The most critical part of the auxiliary cutting mechanism is the toggle cylinder and the core toggle part of the simulation analysis.The maximum stress of the core toggle frame is 5.127 × 10 7 N/m 2 , and the maximum displacement of the core toggle frame during the stress process is 1.281 × 10 −2 mm.The maximum stress of the core frame was much less than the permissible stress of the AISI 1045 steel material, and the strain displacement was within the permissible range.Finite element analysis was used to determine the average diameter of the buds at 2.684 mm, the working pressure of the air pump was 0.442 Mpa, and the cylinder movement speed was 5.068 mm/s.At this time, to determine the machine's two best indicators, namely 74.622% of the shear rate and 18.004% of the damage rate.Experimental data show that the machine can greatly reduce the labor force, liberate the hands of fruit farmers, and has broad application prospects.

Conclusion Author's statement
A PLC-based pomegranate bud cutting device was proposed and designed to address the background of the low efficiency of pomegranate bud high branch cutting, high labor occupation by repetitive manual labor, and high risk factors.The machine structure was designed independently by the author of this study and the feasibility of the machine was experimentally measured.The content of this paper was independently completed by the author of this paper.
The technological innovation and advantages of this device are: 1.This device designs a multi degree of freedom pneumatic end effector, which cooperates with three cylinders: length adjustment cylinder, angle adjustment cylinder, and height adjustment cylinder, to achieve multi angle and all-round cutting of pomegranate sprouts under complex growth conditions, achieving full mechanization of the sprout cutting process and greatly reducing the labor required.2. This device is designed with a multilevel height adjustment mechanism that controls the expansion and contraction of the cylinder to raise and lower the pneumatic platform, thus completing the first-level rough lifting of the device.The second-level lifting device used four stepper motor screw modules to control the stepper motor for precise height adjustment.The mutual cooperation of the first-and second-level lifting devices can achieve complete removal of pomegranate sprouts within different height ranges.3.This device designs a sprout cutting auxiliary leaf-shifting device with dual-cylinder coordination, which enables the device to complete the sprout cutting of branches that need to be trimmed without damaging the main stem of the pomegranate tree.4. The entire control system of the device was controlled by the MCGS.Through the MCGS, it can control the stepper motor, cylinder, and other executing components of the entire device, and display its motion process and status.The entire execution mechanism is controlled by only one screen and related buttons, thereby enhancing the flexibility and practicality of the entire machine operation. https://doi.org/10.1038/s41598-024-55068-8

Figure 1 .
Figure 1.Technology roadmap of pomegranate sprout cutting machine.

Figure 3 .
Figure 3. Working process of pomegranate sprout cutting machine.

Figure 4 .
Figure 4. Structure diagram of the three-dimensional model of the first level lifting device.

Figure 5 .Figure 6 .
Figure 5. Schematic diagram of the structure and mechanism of the first level lifting device.

Figure 9 .
Figure 9. Physical image of the secondary lifting device.

1 .Figure 10 .
Figure 10.Partial enlarged view of pneumatic multi degree of freedom end effector and device.

Figure 11 .
Figure 11.Physical image of camera and related modules.

Figure 12 .
Figure 12.Physical diagram of multi degree of freedom pneumatic end effector.

Figure 13 .
Figure 13.3D model of pomegranate sprouting and tillering assistant cutting device.
. Linear displacement time relationship image of paddle plate

Figure 17 .
Figure 17.Mesh division diagram and force constraint diagram.

Figure 19 .
Figure 19.Physical prototype image of pomegranate sprout cutting machine.

Table 2 .
Graph of acceleration, time, and displacement versus time and velocity versus time.

Table 3 .
Speed time, force time, and linear displacement time relationship of the paddle plate.

Table 4 .
Physical properties of AISI 1045 steel materials.

Table 6 .
Encoding of experimental factors.